Refrigerator

ABSTRACT

A refrigerator provided with a coolant circuit that includes a compressor, a condenser, and an evaporator. The refrigerator also includes a ventilator, such as a fan, for cooling at least one of the condenser and the compressor, and a control system. In an exemplary embodiment of the invention, the control system is structured to detect a failure of the ventilator.

The invention relates to a refrigerator according to the pre-characterizing clause of claim 1.

Refrigeration appliances have become known which have a condenser which has a relatively small installation volume. In order to enable sufficient heat to be transferred from the refrigerant to the ambient air by means of such small-sized condensers, the air that surrounds heat exchanger surfaces of the condenser must be constantly replaced. For that purpose a ventilator or fan is typically used which generates an air current so that the warm air heated on the exchanger surfaces is constantly replaced by cool fresh air. With these types of refrigeration appliances a relatively large volume of the specified installation space is available for storing refrigerated or frozen food items.

Refrigeration appliances having a condenser cooled by means of a fan are very frugal in terms of energy consumption and very reliable in operation. Nevertheless it can happen that the fan stops working. In this case the air surrounding the heat exchanger surfaces of the condenser heats up considerably since it is no longer replaced by cool fresh air. The heat exchange between refrigerant and ambient air is severely constrained as a result. The consequence of this is that the temperature and pressure in the refrigerant circuit increase. This leads to a lowering of the refrigerating capacity of the compressor and consequently the temperature in the compartment requiring to be cooled rises to unacceptable values. The operating time of the compressor can increase up to a state known as continuous duty.

The stored refrigerated or frozen food items can spoil as a result. The refrigerator itself, however, can also suffer considerable damage. Thus, for example, the compressor can be damaged due to the fact that it is not designed for continuous operation. In particular plastic parts which are installed in the area of the condenser can be deformed due to the great heat which is generated in that area and which can no longer be dissipated. In the case of a water-conducting refrigerator this can even result in leakage and water damage, since the water-conducting lines are mostly made of plastic.

The object underlying the invention is to embody a refrigerator in which the condenser and/or compressor are/is cooled by means of a fan in such a way that damage of the aforesaid kind is reliably avoided.

The object is achieved according to the invention by means of a refrigerator having the features recited in claim 1. Because the controller of the refrigerator is designed in such a way that a failure of the fan can be detected, preventive measures can be taken before the refrigerator as such or the refrigerated or frozen food items stored therein can suffer corresponding damage.

The invention is particularly advantageously applied in the case of such refrigerators in which the condenser is disposed in a machine bay in the base of the refrigerator. Since the condenser is housed here in a space which has an opening to the environment on one side only, an exchange of air and cooling of the condenser can scarcely take place without a fan. With this type of appliance the compressor is usually accommodated in the machine bay too, so as well as the heat emission of the condenser there is also the heat emission of the compressor to be added. If there is a buildup of heat in the machine bay, the compressor would very quickly suffer damage not only due to the continuous operation but also due to overheating. Such damage can easily be avoided by means of the invention.

In order to enable the failure of the fan to be reliably detected, the controller can for example check electrical parameters at the fan. In this way the failure of the fan could be detected at a very early stage, even before the machine bay has heated up. Countermeasures could therefore be initiated likewise at a very early stage. However, the controller is advantageously connected to a sensor via which the failure of the fan can be detected.

A flow sensor, for example, could be used as the sensor. Said sensor would likewise respond immediately as soon as the air current for cooling the condenser is no longer being moved. However, not only a failure of the fan would be detected in this way, but also, for example, a blockage of air ducts or ventilation grilles. A flow sensor is relatively complex and expensive, however.

The sensor is particularly advantageously embodied as a temperature sensor. Thus, for example, a very cheap NTC resistor or hot-carrier thermistor can be used which reduces its resistance as the temperature rises. In conjunction with a corresponding diode the NTC resistor could be connected in such a way that the controller receives a corresponding signal only when a predetermined temperature limit value is exceeded.

The temperature sensor could be disposed on the outside of the refrigerator in an area in which the air emerging from the machine bay passes over it. This, though, would have the disadvantage that the controller would not be able to respond to the failure of the fan until after a certain time had elapsed. The temperature sensor is therefore advantageously disposed directly inside the machine bay and measures the temperature prevailing there. As soon as the temperature increases due to a failure of the fan, but also due to blockages in the ventilation system, a corresponding signal is transmitted to the controller.

Alternatively, however, the temperature sensor can also be used to measure the temperature of the condenser and/or compressor directly. For this purpose a temperature sensor can be attached directly to the housing of the condenser and/or compressor. With this exemplary embodiment it would be advantageous that not only the failure of the fan or a blockage of the ventilation ducts could be detected, but also, for example, a short circuit at the compressor motor, which could likewise result in serious damage.

According to the invention the failure of the fan is detected due to a predeterminable limit temperature being exceeded. Said limit temperature must be specified in such a way that a failure of the fan will not be detected already when, for example, a large amount of heat is introduced as a result of the door of the refrigerator being opened at frequent intervals or as a result of a relatively large quantity of still warm frozen or refrigerated food items being stored, and as a consequence the heat at the condenser and in the machine bay also increases over a specific period of time. Such occurrences must not be prematurely and incorrectly interpreted as a failure of the fan. On the other hand the limit value must be set also such that no damage can be caused due to the heat prevailing in the machine bay.

After the set limit temperature is exceeded the compressor is switched off. Usually the fan is only operated when the compressor is also in operation, since heat is dissipated by way of the condenser only while the compressor is operating. The compressor is normally operated until such time as the preset temperature is reached in the interior of the refrigerator. When the limit temperature is reached in the machine bay the compressor will also be switched off even if said preset temperature has not yet been reached in the refrigerator interior.

After the compressor has been switched off, cooling-down will occur in the machine bay due to natural convection. Said cooling-down is detected by the controller by way of the temperature sensor. If no cooling-down is then detected by the controller within a predeterminable period of time, it is inferred from this circumstance that the temperature sensor, not the fan, has failed. In this case the compressor is reactivated by the controller and the normal regulation cycle is started over. At the same time the controller generates a message—on a display for example—which tells the user that the monitoring system is faulty and the field service must be notified.

If, however, the controller detects a dropping of the temperature in the machine bay after the compressor has been switched off, it is assumed that the fan is faulty or the ventilation ducts are blocked. In this case a restarting of the compressor would lead to overheating of the machine bay and to the above-described consequential damage. The refrigerator is therefore switched off by the controller.

To ensure that the stored food items cannot spoil, an audible and/or visual warning signal are/is output if the failure of the fan has been detected by the controller. In this case the field service must be notified very quickly because the temperature in the interior of the refrigerator can only be kept for a few hours in a range in which there is no fear of the stored food items being ruined.

Further details and advantages of the invention will emerge from the dependent claims in connection with the description of an exemplary embodiment which is explained in greater detail with reference to the drawing, in which:

FIG. 1 shows a schematic view of a refrigerator according to the invention.

The refrigerator 1 has an insulated interior 2. The evaporator 4 is mounted on the inside of the rear wall. The electronic controller 3 is located inside the insulation in the lid of the refrigerator. The machine bay 5 is embodied by means of a step in the base of the refrigerator. The machine bay 5 is separated from the interior 2 by way of an insulation layer. The condenser 8 and the compressor 9 are installed in the machine bay 5. In the exemplary embodiment shown here these two components are arranged one above the other. However, refrigerators are also known in which the condenser and the compressor are mounted side by side in the machine bay. A temperature sensor 7 and a fan 6 are also contained in the machine bay 5. The fan 6 is installed in such a way that it extracts air from the back of the refrigerator 1 and forces it into the ventilation duct (not shown here) in the machine bay 5. The ventilation duct is designed in such a way that the extracted air is guided first over the condenser 8 and then over the compressor 9. The air then emerges from the machine bay again near to the fan 6. The temperature sensor 7 is disposed directly in front of the air outlet.

The gaseous refrigerant from the evaporator 4 is compressed in the compressor 9 and heats up in the process. From the compressor 9 it flows into the condenser 8. Here the refrigerant is cooled by the air blown in by the fan 6 and in the process transitions into the liquid aggregate state. The liquid and cooled refrigerant flows into the evaporator, expands and transitions into the gaseous state. Extreme cooling-down is associated with this change in the aggregate state. The cold refrigerant is now able to absorb heat from the interior 2 of the refrigerator 1. The compressor 9 is always activated by the electronic controller 3 when the temperature in the insulated interior 2 exceeds a preset maximum temperature.

The fan 6 is normally put into operation by the controller 3 only when the compressor 9 is also active. Mostly, however, the fan 6 is activated with a certain lag so that the heat generated by the compressor 9 and the condenser 8 can continue to be dissipated from the machine bay 5 even after the compressor 9 has been switched off.

If the fan 6 is defective, no cool ambient air is blown through the ventilation duct even during the operation of the compressor 9, which means that the heat can no longer be discharged from the condenser 8 to the outside. In this case the air which is no longer moving inside the machine bay 5 heats up above a preset limit value. This heat buildup would result in plastic parts in the vicinity of the machine bay 5 being deformed. Because the refrigerant is no longer being cooled down sufficiently, the temperature in the interior 2 of the refrigerator 1 can no longer be reduced accordingly even when the compressor 9 is running Consequently the compressor 9 would carry on running continuously because the switch-off temperature would never be reached in the interior 2. The compressor 9 can be damaged as a result of this continuous operation.

The temperature sensor 7 is provided in order to prevent the consequences of a faulty fan. Said temperature sensor passes a signal to the electronic controller 3 as soon as the air inside the machine bay 5 exceeds a limit temperature. The controller 3 thereupon switches off the compressor 9 immediately, regardless of whether the switch-off temperature has already been reached in the interior 2. Even after the compressor 9 has been switched off, the temperature sensor 7 continues to be monitored by the electronic controller 3. Since with the compressor 9 switched off the temperature in the motor bay 5 ought also slowly to decrease, the temperature sensor 7 should also be able to detect this drop in temperature. Thus, if no temperature reduction in the machine bay 5 is measured by the temperature sensor 7 after a predetermined period of time has elapsed, the electronic controller 3 detects a fault in the temperature sensor 7. The compressor 9 will thereupon be restarted and operated further until the switch-off temperature has been reached in the interior 2 of the refrigerator 1. In this case a message is generated for the user of the refrigerator 1 prompting him or her to notify the field service.

If, on the other hand, a temperature reduction in the machine bay 5 is measured by the temperature sensor 7 after the predetermined period of time has elapsed, the electronic controller 3 detects a fault in the air circulation through the machine bay 5. In most cases a fault in the fan 6 is responsible for this. Blockages in the ventilation duct, caused, for example, by a great accumulation of dust, may also have formed, however. In these cases the refrigerator 1 will be switched off completely by the electronic controller 3 in order thereby to prevent the already described consequential damage.

To ensure the user is made aware that the refrigerator 1 has been switched off, a corresponding display is generated on a display (not shown in the drawing) which is normally installed in the front side of the lid directly in front of the electronic controller 3. It has to be assumed, however, that this display too would be noticed too late by the user. For this reason an acoustic signal is generated in addition in order to prompt the user to read the message on the display. In this case the field service must be notified immediately by the user so that the fault can be repaired in the next few hours. In this way the spoiling of the food items stored in the appliance can also be prevented.

LIST OF REFERENCE SIGNS

-   1 Refrigerator -   2 Interior -   3 Electronic controller -   4 Evaporator -   5 Machine bay -   6 Fan -   7 Temperature sensor -   8 Condenser -   9 Compressor 

1-10. (canceled)
 11. A refrigerator, comprising: a refrigerant circuit, the refrigerant circuit including a compressor, a condenser, and an evaporator; a fan structured to cool at least one of the condenser and the compressor; and a controller, wherein the controller is structured to detect a failure of the fan.
 12. The refrigerator as claimed in claim 11, wherein at least one of the condenser and the compressor are disposed in a machine bay in a base of the refrigerator.
 13. The refrigerator as claimed in claim 11, wherein the controller is structured to communicate with at least one sensor.
 14. The refrigerator as claimed in claim 13, wherein the at least one sensor is a temperature sensor.
 15. The refrigerator as claimed in claim 14, wherein the temperature sensor is structured to measure a temperature in a machine bay in a base of the refrigerator.
 16. The refrigerator as claimed in claim 14, wherein the temperature sensor is structured to measure a temperature of at least one of the condenser and the compressor.
 17. The refrigerator as claimed in claim 14, wherein the controller is structured to detect when a temperature in at least one of the machine bay, the condenser, and the compressor has exceeded a predetermined limit temperature and to switch off at least the compressor when the predetermined limit temperature is exceeded.
 18. The refrigerator as claimed in claim 17, wherein the controller is structured to detect a fault in the temperature sensor when the predetermined limit temperature is not undershot after a predetermined period of time has elapsed.
 19. The refrigerator as claimed in claim 17, wherein the controller is structured to detect the failure of the fan when the predetermined limit temperature is undershot after a predetermined period of time has elapsed after the compressor has been switched off.
 20. The refrigerator as claimed in claim 11, wherein at least one of an audible warning signal and a visual warning signal is output when the failure of the fan is detected. 